Moved depends to imports

All depends have now been moved to Imports. I'll shortly switch everything over from legacy RCurl to httr as well but for now no package functionality has been broken.

Signed-off-by: Karthik Ram <karthik.ram@gmail.com>
Added a build ignore list

Signed-off-by: Karthik Ram <karthik.ram@gmail.com>
Updated documentation

Signed-off-by: Karthik Ram <karthik.ram@gmail.com>
Package rebuild

Now namespace is correct with Imports, updated news file. Will push to CRAN once I switch everything over to httr.

Signed-off-by: Karthik Ram <karthik.ram@gmail.com>